The present application claims priority to Japanese patent application of Fujita et al, filed Sep. 26, 2000, No.2000-293164, and Japanese patent application of Fujita et al, filed Sep. 26, 2000, No.2000-293166, the entirety of each is hereby incorporated into the present application by this reference.
1. Field of the Invention
The present invention relates to a steering wheel for a vehicle having an airbag apparatus. More particularly, the invention relates to a steering wheel having an airbag apparatus and in which switch operating portion of a function part is disposed. Examples of the function part are drive monitor switch, constant-speed running apparatus, audio equipment, air conditioner equipment, navigation system, telephone, shift change and the like.
2. Description of Related Art
Conventionally, a steering wheel having an airbag apparatus is know in Japanese Patent Applications Laid-open No.100907/1998 and No.11246/1999. The airbag apparatus comprises an airbag, an inflator, a pad and a bag holder. The airbag is folded such that the airbag can expand. The inflator supplies expansion gas to the airbag. The pad covers the folded airbag. The bag holder holds the airbag, the inflator and the pad, and is connected to a steering wheel body.
The pad includes a door that is pushed by the expanding airbag and opened. The door is provided at its periphery with a to-be ruptured portion, and is provided at its portion of an outer periphery with a hinge. The door is pushed when the airbag expands to rupture the to-be ruptured portion, and opens around the hinge as a rotation center.
In these days, it is increasingly required to dispose switch operating portions for the function part that are drive monitor switch, constant-speed running apparatus, audio equipment, air conditioner equipment, navigation system, telephone, shift change and the like on the pad of the boss or the spokes near the boss. These switch operating portions are constituted such that they can be operated from above. That is, the switch operating portion comprised operation button or operation lever operated by being pushed downward or swung. In order to facilitate the operation of the switch operating portion, the switch operating portion is disposed upward such that its operating surface approaches a ring surface. The ring surface is the plane formed by an upper surface of a ring when the steering wheel is viewed from a direction perpendicular to a steering shaft.
However, when the airbag is developed and expanded when a driver is close to the steering wheel, it is necessary that the airbag does not apply a partial pushing force to the driver. For this purpose, it is preferable to develop the airbag widely at initial stage of expansion and to inflate the airbag toward the driver. At that time, if the door of the pad interferes with the switch operating portion uselessly, the door can not open widely. That is, the airbag at its initial expanding stage can not be developed widely.
In the present specification, the upper-lower, front-rear and right-left directions are based on the steering shaft when the steering wheel is mounted to the vehicle unless otherwise stated. That is, the upper-lower direction in the present specification is a vertical direction along the axial direction of the steering shaft. The front-rear direction in the present specification is the front and rear direction (a longitudinal direction) of the vehicle along a direction perpendicular to the axis of the steering shaft when the steering wheel is steered straightly.
The present invention solves the above problems. That is, the present invention provides a steering wheel having an airbag apparatus capable of widely open a door of a pad even if a switch operating portion is disposed.
A first steering wheel having an airbag apparatus of the present invention has the following structure. That is, the steering wheel comprises a ring grasped at the time of steering, a boss disposed on a center of the ring, three spokes for connecting the ring and the boss, and a space between the spokes. The steering wheel also includes, as constituent parts, a steering wheel body, the airbag apparatus disposed on the boss, and a switch operating portion that can be operated from above. The switch operating portion is disposed at least one of the boss and the spoke. The airbag apparatus comprises an airbag folded such that the airbag can expand, an inflator for supplying expansion gas to the airbag, a pad for covering the folded airbag. Further the airbag apparatus comprises a bag holder connected to the steering wheel body for holding the folded airbag, the inflator and the pad. The pad includes three doors such that one opening through which the airbag projects can be formed in a center of the pad. Each of the doors is provided at its periphery with to-be ruptured portion. And hinges are disposed on the periphery side of each of the doors. The door is pushed by the airbag when it is expanded and the to-be ruptured portion is ruptured, the door opens around a hinge disposed on the side of an outer periphery of the pad as a rotation center. A pad is held against the bag holder in the proximity to the hinge of each of the doors. The hinge of each of the doors is disposed at a position near the space between the spokes, and on the side of an outer periphery of the pad that is lower than an portion above a holding portion by the bag holder near the hinge. Each of the doors is disposed in the three spaces between the spokes when the door opens around the hinge as a rotation center. The switch operating portion is disposed on an area other than the doors and on the boss or the spoke that is not covered with the door when it opens.
According to the first steering wheel of the present invention, if the airbag is expanded to push the three doors of the pad, each of the doors of the pad ruptures the to-be ruptured portion there around and opens around the hinge as the rotation center.
At that time, the hinge of each door is disposed at a position near the space between the spokes and at the side of the outer periphery of the pad lower than a portion above the holding portion by the bag holder near the hinge. Thus, the door opens around the hinge as the rotation center at a position lower than the outer periphery of the pad. That is, the door can secure the wide area of its own and can open as wide as possible.
If the hinge of the door is disposed above the holding portion by the bag holder, the area of the door itself becomes narrow. Thus, the door can not open widely.
Further, the switch operating portion is disposed in an area other than the doors, but of a boss or a spoke that is not covered with the doors when they open. When doors open around the hinge as the rotation center, the doors are arranged so as to be disposed in the three spaces between the spokes. The opened doors are disposed smoothly in the three spaces between the three spokes without interference with the switch operating portion. A widely opening state of each door can stably be secure.
Therefore, according to the first steering wheel having the airbag apparatus of the present invention, even if the switch operating portion is disposed in an area of the boss or the spoke, the doors of the pad can widely open. Thus, in the first steering wheel, the initial expanding airbag can widely develop.
It is preferable that the to-be ruptured portion at a portion of the adjacent doors is substantially T-shape as viewed from above. That is, the to-be ruptured portion has a lateral line portion disposed in the right-left direction and a longitudinal line portion extending rearward from a substantially central portion of the lateral line portion. The left and right opposite ends of the lateral line portion are directed to disposition directions of the front left and right spokes of the spokes, and a rear end of the longitudinal line portion is directed to a disposition direction of the rear spoke in the spoke. With this steering wheel, the following working effect can be obtained.
That is, in the three spokes type steering wheel, the front space is set greater than rear left and right spaces so that the measuring instruments of the instrument panel can easily be seen. Therefore, if the to-be ruptured portions adjacent to the doors are substantially T in shape, the front door in front of the lateral line portion of the to-be ruptured portion has a greater area. The left and right doors divided by the rear longitudinal line portion that is behind the lateral line portion have a smaller area. As a result, shapes of the front, left and right doors can easily be fit to the front, left and right spaces in which the doors are accommodated when they opens. That is, the shapes of the front, left and right doors can easily be set.
Further, the pad may be provided with the following ceiling wall and side wall. The ceiling wall is disposed on an upper portion of the pad and has the doors and the to-be ruptured portion. The side wall extends downward from the ceiling wall and is disposed in the vertical direction such that the side wall can be connected to the bag holder. A remaining portion of the to-be ruptured portion except adjacent portions which adjoin the doors is disposed close to an inner surface of the side wall of the ceiling wall and substantially along the side wall. With this pad, the following working effect can be obtained.
That is, the side wall of the pad increases the thickness of the ceiling wall. Then the remaining portion of the to-be ruptured portion except adjacent portions of the doors approaches the inner surface of the side wall portion which increases the thickness of the ceiling wall. Therefore, stress concentration is prone to be generated in the remaining portions. Further, the remaining portions are disposed along the general portion of the side wall. Therefore, the remaining portions rupture easily along the general portion. As a result, the to-be ruptured portion easily ruptures and the doors smoothly open.
Further, it is preferable that three clots when the airbag is folded are disposed below the front, left and right doors. With this structure, when the airbag is developed and expanded, the front, left and right doors are reliably pushed by the folded portions disposed below, and the airbag can smoothly open.
A second steering wheel having an airbag apparatus of the present invention has the following structure. That is, the steering wheel comprises a ring grasped at the time of steering, a boss disposed on a center of the ring, and a spoke for connecting the ring and the boss. The airbag apparatus is disposed on an upper portion of the boss. The airbag apparatus comprises an airbag that is folded such that it can be expanded, and a pad for covering the folded airbag. The pad includes a door that is pushed and opened by the expanding airbag. A switch operating portion is disposed below the door when it is opened. The switch operating portion is disposed in a non-limited region where an opening-completion state of the door is not limited for the door that has completed its opening operation.
According to the second steering wheel of the invention, if the airbag is expanded to push the door of the pad, the door opens, and the airbag projects from the pad. At that time, the switch operating portion is disposed in the non-limited region where the opening-completion state of the door is not limited to the door when it has been opened. Thus, the door can complete its opening in a widely opened state without limited by the switch operating portion.
Thus, according to the second steering wheel having the airbag apparatus of the present invention, even if the switch operating portion is disposed below the pad door when the door opens, the pad door can be opened widely. Thus, in the second steering wheel, the airbag in its initial expanding state can be widely developed.
This second invention is not limited to the three spoke type steering wheel, and the invention can also be applied to two or four spoke type steering wheel. The number of the doors of the pad is not limited to three, and one or more doors may be provided.
In the second steering wheel, it is preferable that the switch operating portion is disposed in the non-limited region when the switch operating portion is pushed and moved by the door when it opens. With this structure, in a normal state before the door opens, the switch operating portion can be disposed near the ring surface located upper position. Thus, in the second steering wheel, even if the switch operating portion is disposed below the pad door when it opens, a widely opening state of the door can be secured, and the operability of the switch operating portion becomes excellent.
In this case, when the switch operating portion is pushed and moved by the door, the switch operating portion may be lowered into the non-limited region.
When the switch operating portion includes an operation button that is pushed down for operation, the switch operating portion may be constructed as follows. That is, it is preferable that when the switch operating portion is pushed and moved by the door, the switch operating portion is rotated and moved in the lateral direction that intersects with an operation direction of the operation button substantially at right angles so that the switch operating portion is moved to the non-limited region. In this case, even if the operation button that must be operated downward strongly at the time of operation is disposed on the switch operating portion, no problem is caused. This is because even if the switch operating portion is pushed down unnecessarily strongly during normal operation, the switch operating portion is not prone to move into the non-limited region. Thus the operability of the switch operating portion is stabilized.
Of course, in the second steering wheel, the switch operating portion may previously disposed in the non-limited region of the door.